Medicare Part D plans tighten drug coverage more than commercial plans, study finds

A National Pharmaceutical Council analysis of 2024-2026 formulary data says Medicare Part D plans restricted coverage in competitive drug classes more often than commercial plans after the Inflation Reduction Act took effect. The findings raise new concerns about beneficiary access as the Medicare drug benefit continues to change.

Why it matters: - Medicare beneficiaries may be losing access to previously covered brand-name medicines at a higher rate than people with commercial insurance. - The changes affect competitive drug classes, where plan coverage decisions can shape access and out-of-pocket costs. - The findings add to concerns about unintended coverage shifts after the Inflation Reduction Act changed Part D design.

What happened: - The National Pharmaceutical Council published research in Health Affairs Scholar analyzing 2024-2026 formulary data. - The study examined brand-only medicines in competitive drug classes across Medicare standalone prescription drug plans and Medicare Advantage prescription drug plans. - Commercial insurance served as the comparison group. - Competitive classes were defined as classes with at least three commercially available, eligible brand-only drugs. - The study found Medicare Part D plans were more likely than commercial plans to restrict drug coverage after implementation of the Inflation Reduction Act.

The details: - The Inflation Reduction Act introduced major Part D changes, including a cap on patient out-of-pocket costs and increased catastrophic-phase liability for plans and manufacturers effective Jan. 1, 2025. - The analysis says incentives to exclude drugs may be highest in therapeutic classes with multiple branded medicines, where plans can use formulary exclusions to seek higher rebates. - On average, 4.5 million Medicare beneficiaries, including 2.7 million in PDPs and 1.8 million in MA-PD plans, lost insurance coverage for previously covered branded medicines across 16 competitive classes. - Medicare coverage declined in both 2025 and 2026, with larger reductions in standalone PDPs than in MA-PD plans. - In 2024, the average share of beneficiaries with coverage was highest in commercial plans at 71.4%, compared with 52.3% in MA-PD plans and 47.4% in PDP plans. - At the drug level, coverage decreases from 2024-2026 affected more than 5% of beneficiaries for over half of included drugs in PDP plans, or 30 of 59 drugs. - Those PDP drug-level declines represented at least 1.14 million fewer beneficiaries covered per drug. - At the class level, average coverage fell by at least five percentage points from 2024-2026 in 10 of 16 classes in PDPs, seven of 16 in MA-PD plans, and three included classes in commercial plans. - Dr. Campbell, a study co-author and NPC chief science officer, said the research shows beneficiaries are losing coverage for certain drugs at a higher rate than those with commercial insurance.

Between the lines: - The results suggest Part D plan design changes may be producing broader formulary tightening than expected. - The gap between Medicare and commercial coverage points to a Medicare-specific access issue, not just a general market trend. - The study’s class-level and drug-level declines suggest the effect is not isolated to one or two medicines.

What's next: - The authors said more research is needed as IRA implementation continues. - The findings point to a need to monitor Medicare patients’ access to medicines, health outcomes and Part D formulary review processes. - Further changes in Medicare coverage may emerge as plans continue adjusting to the IRA landscape. - More information is available in the National Pharmaceutical Council announcement.